It is predicted that the most change in color (and in wavelength and absorption) will occur when the basic pH solution is added to the three teas.
Abstract:
EFFECTS OF pH ON TEA PIGMENTATION. Ruth Sheldon. Lily Rogers-Grant and Ariana Amini. Research was conducted to obtain a better understanding of the effects acids and bases have on the pigmentation of teas. Knowledge of anthocyanins and their pH sensitivity has been applied to test the effects of of three different pH buffers on three different types of tea. It was found that the absorption of all samples was stable over the pH range tested. All absorption levels peaked within the blue wavelength of the spectrum. Anthocyanins and their pH sensitivity can be applied to the larger world of food production, as it is known that anthocyanins have the potential to dye things different colors; and in addition are known to be relatively healthy with the antioxidant-like qualities they posses. A natural occurring dye could be marketed to many people as a healthy alternative to Red 40 and Yellow 5. In the future, the same teas could be added to buffers with more extreme pH. It is possible that a more dramatically acidic or basic substance could produce a color change. Keywords: Spectrophotometer, Anthocyanin, Wavelength, Buffer, Acidic Solution, Basic Solution
Withers, G. (n.d.). Natural Indicators: How do they work?. Carnegie Mellon University//. Retrieved February 25, 2012, from www.cmu.edu/gipse/materials/pdf-2001/natural_ph_indicators.pdf
Lab Procedure:
1. Collect 3 different kinds of tea, mass one bag of each and record data in table. 2. Boil one bag of each tea in a beaker with 100 ml of water on a hot plate for 6 minutes at high temperature. When done, seal with parafilm and put in the refrigerator for one day. 3. Obtain a capsule of a buffer solution for a ph of 4, 7, and 10. Empty each capsule into a separate 250 ml Erlenmeyer flask, add 100 ml distilled water and stir. 4. Using a pipette, place 3 samples of each tea in a cubette and put in a holder. 5. Record the initial color and spectrometer reading of each tea. 6. Place 4-10 drops of the ph 7 buffer solution into one of the cubes for each tea, stop when the tea starts to turn color. Record the number of drops and after a few minutes, the final color of the tea. 7. Repeat for ph 4 and ph 10 and each type of tea. 8. Plug in spectrometer into computer and calibrate. 9. Using the spectrometer, record the reading for each sample of tea and record.
Apparatus & Chemicals Needed:
Red Zinger, Apple cinnamon, and Licorice tea bags
Water
Beakers
3 250 ml Erlenmeyer flasks
Hot plate
Capsules of buffer solution for ph 4, 7, and 10
6 disposable pipettes
Spectrometer
Computer
9 Cubettes
Cubette holder
Safety Information:
No special precautions must be taken in this experiment because all materials are used in daily life and do not harm the human body. Although no dangers are indicated, normal lab procedure will be followed.
goggles
Table 1: Phase 2, Tea and solutions
Red Zinger
Baking Soda
Apple Cider Vinegar
Volume (in each cuvette)
4 drops
3 mL
3 mL
Color
dark red
clear with white
light orange
pH
7
8
3
Table 2: Phase 2, Spectrometer Data for tea added to acid/base
Project Title:
The Effect of Acids and Bases on Pigments in TeasProject Topic:
Acids and BasesChemistry Concept:
Plant Pigment Chemistry and Acid-Base IndicatorsHypothesis:
It is predicted that the most change in color (and in wavelength and absorption) will occur when the basic pH solution is added to the three teas.Abstract:
EFFECTS OF pH ON TEA PIGMENTATION. Ruth Sheldon. Lily Rogers-Grant and Ariana Amini.Research was conducted to obtain a better understanding of the effects acids and bases have on the pigmentation of teas. Knowledge of anthocyanins and their pH sensitivity has been applied to test the effects of of three different pH buffers on three different types of tea. It was found that the absorption of all samples was stable over the pH range tested. All absorption levels peaked within the blue wavelength of the spectrum. Anthocyanins and their pH sensitivity can be applied to the larger world of food production, as it is known that anthocyanins have the potential to dye things different colors; and in addition are known to be relatively healthy with the antioxidant-like qualities they posses. A natural occurring dye could be marketed to many people as a healthy alternative to Red 40 and Yellow 5. In the future, the same teas could be added to buffers with more extreme pH. It is possible that a more dramatically acidic or basic substance could produce a color change.
Keywords: Spectrophotometer, Anthocyanin, Wavelength, Buffer, Acidic Solution, Basic Solution
Journal Articles:
http://journals.tubitak.gov.tr/biology/issues/biy-10-34-1/biy-34-1-7-0805-14.pdfNikka, E. (2008). The effect of ascorbic acid and h2o2 treatment on the stability of anthocyanin pigments in berries. 7.Retrieved from http://journals.tubitak.gov.tr
http://web.ebscohost.com/ehost/detail?vid=5&hid=106&sid=6aea3d6d-5452-4451-89df-4d326cd8004a%40sessionmgr113&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=aph&AN=16184546
Dall'Orto, V. C. (2005). Comparison of tyrosinase biosensor and colorimetric method for polyphenol analysis in different kinds of teas. Retrieved from
http://web.ebscohost.com/ehost/search/basic?sid=6aea3d6d-5452-4451-89df-4d326cd8004a%40sessionmgr113&vid=6&hid=106
Epp, D. N. (n.d.). Teas as natural indicators. EBSCO host, 70(4), 326. Retrieved from
https://docs.google.com/viewer?a=v&pid=gmail&attid=0.1&thid=134c3d36e862a3d8&mt=application/pdf&url=https:mail.google.com/mail/u/0/?ui%3D2%26ik%3D78c846a99d%26view%3Datt%26th%3D134c3d36e862a3d8%26attid%3D0.1%26disp%3Dsafe%26zw&sig=AHIEtbQZf-57Gw8YujydLb0UgbGfuyRsHA
Withers, G. (n.d.). Natural Indicators: How do they work?. Carnegie Mellon University//. Retrieved February 25, 2012, from www.cmu.edu/gipse/materials/pdf-2001/natural_ph_indicators.pdf
Lab Procedure:
1. Collect 3 different kinds of tea, mass one bag of each and record data in table.2. Boil one bag of each tea in a beaker with 100 ml of water on a hot plate for 6 minutes at high temperature. When done, seal with parafilm and put in the refrigerator for one day.
3. Obtain a capsule of a buffer solution for a ph of 4, 7, and 10. Empty each capsule into a separate 250 ml Erlenmeyer flask, add 100 ml distilled water and stir.
4. Using a pipette, place 3 samples of each tea in a cubette and put in a holder.
5. Record the initial color and spectrometer reading of each tea.
6. Place 4-10 drops of the ph 7 buffer solution into one of the cubes for each tea, stop when the tea starts to turn color. Record the number of drops and after a few minutes, the final color of the tea.
7. Repeat for ph 4 and ph 10 and each type of tea.
8. Plug in spectrometer into computer and calibrate.
9. Using the spectrometer, record the reading for each sample of tea and record.
Apparatus & Chemicals Needed:
Red Zinger, Apple cinnamon, and Licorice tea bagsWater
Beakers
3 250 ml Erlenmeyer flasks
Hot plate
Capsules of buffer solution for ph 4, 7, and 10
6 disposable pipettes
Spectrometer
Computer
9 Cubettes
Cubette holder
Safety Information:
No special precautions must be taken in this experiment because all materials are used in daily life and do not harm the human body. Although no dangers are indicated, normal lab procedure will be followed.goggles
Table 1: Phase 2, Tea and solutions
Table 2: Phase 2, Spectrometer Data for tea added to acid/base
trial 1 - 403.4
trial 2 - 403.4
trial 1 - 1.3
trial 2 - 1.2
trial 1 - 403.4
trial 2 - 403.4
trial 1 - 0.75
trial 2 - 0.43